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93 lines
4.2 KiB
HTML
93 lines
4.2 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This manual describes how to install and use the GNU multiple precision
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arithmetic library, version 6.1.0.
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Copyright 1991, 1993-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document under
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the terms of the GNU Free Documentation License, Version 1.3 or any later
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version published by the Free Software Foundation; with no Invariant Sections,
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with the Front-Cover Texts being "A GNU Manual", and with the Back-Cover
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Texts being "You have freedom to copy and modify this GNU Manual, like GNU
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software". A copy of the license is included in
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GNU Free Documentation License. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Assembly SIMD Instructions (GNU MP 6.1.0)</title>
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<meta name="description" content="How to install and use the GNU multiple precision arithmetic library, version 6.1.0.">
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<meta name="keywords" content="Assembly SIMD Instructions (GNU MP 6.1.0)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="Assembly-Coding.html#Assembly-Coding" rel="up" title="Assembly Coding">
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<link href="Assembly-Software-Pipelining.html#Assembly-Software-Pipelining" rel="next" title="Assembly Software Pipelining">
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<link href="Assembly-Floating-Point.html#Assembly-Floating-Point" rel="prev" title="Assembly Floating Point">
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<style type="text/css">
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Assembly-SIMD-Instructions"></a>
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<div class="header">
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<p>
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Next: <a href="Assembly-Software-Pipelining.html#Assembly-Software-Pipelining" accesskey="n" rel="next">Assembly Software Pipelining</a>, Previous: <a href="Assembly-Floating-Point.html#Assembly-Floating-Point" accesskey="p" rel="prev">Assembly Floating Point</a>, Up: <a href="Assembly-Coding.html#Assembly-Coding" accesskey="u" rel="up">Assembly Coding</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="SIMD-Instructions"></a>
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<h4 class="subsection">15.8.7 SIMD Instructions</h4>
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<a name="index-Assembly-SIMD"></a>
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<p>The single-instruction multiple-data support in current microprocessors is
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aimed at signal processing algorithms where each data point can be treated
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more or less independently. There’s generally not much support for
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propagating the sort of carries that arise in GMP.
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</p>
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<p>SIMD multiplications of say four 16x16 bit multiplies only do as much
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work as one 32x32 from GMP’s point of view, and need some shifts and
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adds besides. But of course if say the SIMD form is fully pipelined and uses
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less instruction decoding then it may still be worthwhile.
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</p>
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<p>On the x86 chips, MMX has so far found a use in <code>mpn_rshift</code> and
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<code>mpn_lshift</code>, and is used in a special case for 16-bit multipliers in the
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P55 <code>mpn_mul_1</code>. SSE2 is used for Pentium 4 <code>mpn_mul_1</code>,
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<code>mpn_addmul_1</code>, and <code>mpn_submul_1</code>.
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</p>
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</body>
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</html>
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